The words I also heard were, "If there's only even a 1% chance that Clipper has been compromised, the whole thing's over. We have to start from scratch." What does it mean to ``compromise'' Clipper? The algorithm is known? Yeah.. this doesn't completely add up unless (a) the source is lying or (b) there's a "blatant" back door. If the algorithm becomes known at this stage in the game, they can probably "easily" generate a modified SKIPJACK algorithm (changing the S-boxes or equivalent), a new family key, and a subtle variation on key generation. They might not even need to re-spin the chip design if, as they claimed, the critical parts of the algorithm are programmed into the chip after fabrication. BTW, my guess at the most likely back door is that the unit keys will be generated as a cryptographic function of the serial number and a *small* random number generated for each chip and unknown to the agency. They would have to search a mere 2**16..2**32 keys once they get the serial number out of the LEEF. The existance of such a backdoor would be difficult to prove, since there would be no visible evidence for it in the individual chips. It is also difficult to disprove such a theory because the clipper key generation algorithms are classified. - Bill